In the GAA−/− 129SVE mouse model of Pompe Disease, robust IgG1 antibody generation against human rhGAA is driven by immunodominant CD4+ Th2 cell epitopes, and these affected mice with high IgG antibody titers ultimately die from IgE-mediated anaphylaxis (22, 23). The gene discussed is CD4; the disease is Glycogen storage disease due to acid maltase deficiency.